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112 results on '"Stietz, F."'

12. Quantitative optical determination of the shape of Cu nanocrystals in a composite film.

Author

Gonzalo, J., Serna, R., Afonso, C. N., Bosbach, J., Wenzel, T., Stietz, F., Tra¨ger, F., Babonneau, D., and Hole, D. E.

Subjects
COPPER crystals, NANOSTRUCTURED materials, AMORPHOUS semiconductors, PLASMONS (Physics), COMPOSITE materials
Abstract

We demonstrate that optical extinction spectroscopy can be used to determine the effective shape of Cu nanocrystals (NCs) embedded in a transparent amorphous Al[sub 2]O[sub 3] host both produced by pulsed laser deposition. The axial ratio of the NCs was extracted from the positions of the surface plasmon modes of the optical extinction spectra of the nanocomposite film. Comparison to the results obtained by grazing incidence small angle x-ray scattering shows excellent agreement. Thus, optical spectroscopy can be used as a simple, easily accessible, and versatile tool for the characterization of the NCs that form nanocomposite films. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Published
2001
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15. Lighting the way ahead: Photonics21 Strategic Research Agenda

Author

Audren, J. T., Andersson, J., Baets, R., Bieller, S., Bindig, P., Bigo, S., Blochwitz Nimoth, J., Carter, A., Clapp, T., Cotter, D., Dämmig, M., Dainty, C., De Silvestri, S., Dominguez, C., Elbers, J. P., Everett, J., Fischer, R., Fonjallaz, P. Y., Friedel, A., Fulbert, L., Gosselin, S., Grallert, H. J., Grillet, A., Gucciardi, P. G., Haskal, E., Herzig, H. P., Jalocha, A., Jonathan, J. M., Judson, J. P., Kaierle, S., Klemmt, M., Knapp, W., Larkins, E., Lebby, M., Mayerhöfer, T., Milanese, Daniel, Mohr, J., Napier, B., Nayar, B., Parker, M., Pearsall, T., Pickering, C., Piegari, A., Popp, J., Ramponi, R., Ristau, D., Robin, T., Sandner, W., Sarger, L., Smets, B., Smit, M., Stietz, F., Svanberg, K., Thienpont, H., Thylén, L., Torner, L., Tremont, M., Viglienzoni, A., Visser, P., Wale, M., Walf, G., Walker, S., Wessler, B., and Wittrock, U.

Published
2010

38. Silicon nanoclusters formed through self-assembly on CaF[sub 2] substrates: morphology and optical properties.

Author

Andersson, M., Iline, A., Stietz, F., and Träger, F.

Subjects
SILICON, NANOSTRUCTURED materials, DIFFUSION, NUCLEATION
Abstract

Abstract. We studied the influence of the size and shape of silicon nanoclusters on their optical response. For this purpose, clusters were prepared by deposition, and subsequent diffusion and nucleation, of Si atoms on CaF[sub 2] substrate surfaces. By varying the growth parameters, oblate aggregates with sizes of between 5 and 30 nm and axial ratios between almost unity and 0.1 were generated. We found that the substrate temperature during growth predominantly influences the diameter and number density of the particles, whereas the coverage and deposition rate determine the axial ratio. Optical extinction was measured in the photon energy range between 1.0-6.0 eV and compared to model calculations. The mean size of the Si clusters mainly determines the absolute magnitude of the optical extinction. In contrast, the axial ratio drastically affects the overall structure of the spectra and the relative importance of three identified maxima. The most essential and interesting reason for the pronounced influence of the particle shape on the optical properties is a shift of the valence band plasmon in the silicon nanoparticles from an energy of above 9.0 eV for spherical clusters into the ultraviolet spectral range to about 5 eV for axial ratios below 0.3. [ABSTRACT FROM AUTHOR]

Published
2000

39. Laser-induced manipulation of the size and shape of small metal particles: Towards monodisperse clusters on surfaces.

Author

Bosbach, J., Martin, D., Stietz, F., Wenzel, T., and Träger, F.

Abstract

A novel experimental technique is presented for post growth narrowing of the size distribution of metal nanoparticles on dielectric substrates. In order to demonstrate the potential of the method, oblate Ag clusters with mean radii of < R>=6 nm and broad size distributions were prepared under ultrahigh vacuum conditions on quartz substrates. Narrowing of the width of their size distribution was accomplished by irradiation with short laser pulses. The laser light excites plasmons in the particles, the frequency of which depends on the size and shape of the clusters. By choosing the light frequency such that only the smallest and the largest particles selectively absorb light, evaporate atoms and shrink in size, the size distribution was narrowed by 40%. A scenario for producing monodisperse particles is discussed. [ABSTRACT FROM AUTHOR]

Published
2000
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